The purpose of the proposed research is to develop a practical and precise method for determining absorbed-dose distributions from high-energy electron beams for use in cancer treatment planning, particularly in cases complicated by inhomogeneities such as bone and lung tissue, and by body curvature. This goal will be accomplished through the generalization to high-energy electron beams of Fermi age diffusion theory, which is used in dealing with the problem of neutron moderation in nuclear reactors. The present investigators have already derived the basic equations of this method, which is comprised of three stages: reduction to the diffusion situation, analysis of the diffusion situation, and calculation of absorbed dose distribution. However, in order to be clinically useful, the Fermi age method will have to be developed both by further theoretical research and, equally importantly, by systematic examination of experimental data. Special experiments carried out with The University of Chicago's therapeutic electron linear accelerator, which operates with a scanning pencil-beam, will augment already-published experimental data, and data-processing work (particularly Monte-Carlo computer calculations) will play a major role in the research. Through this experimental and theoretical research, an algorithm for computer calculation of dose distribution from high-energy electron beams will be developed, taking into account the presence of inhomogeneities and body curvature. The end result will be a practical method of cancer treatment planning applicable generally to clinical situations involving high-energy electron beams.